Optofluidic devices are capable of detecting single molecules, but greater sensitivity and specificity is desired through hydrodynamic focusing (HDF). Three-dimensional (3D) hydrodynamic focusing was implemented in 10-μm scale microchannel cross-sections made with a single sacrificial layer. HDF is achieved using buffer fluid to sheath the sample fluid, requiring four fluid ports to operate by pressure driven flow. A low-pressure chamber, or pit, formed by etching into a substrate, enables volumetric flow ratio-induced focusing at a low flow velocity. The single layer design simplifies surface micromachining and improves device yield by 1.56 times over previous work. The focusing design was integrated with optical waveguides and used in order to analyze fluorescent signals from beads in fluid flow. The implementation of the focusing scheme was found to narrow the distribution of bead velocity and fluorescent signal, giving rise to 33% more consistent signal. Reservoir effects were observed at low operational vacuum pressures and a balance between optofluidic signal variance and intensity was achieved. The implementation of the design in optofluidic sensors will enable higher detection sensitivity and sample specificity.

中文翻译：

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用单个牺牲层形成的微尺度光流控通道中的 3D 流体动力聚焦。


光流控装置能够检测单分子，但需要通过流体动力聚焦（HDF）获得更高的灵敏度和特异性。三维 (3D) 流体动力聚焦在由单个牺牲层制成的 10 微米级微通道横截面中实现。 HDF 是使用缓冲液包裹样品液来实现的，需要四个流体端口通过压力驱动流进行操作。通过蚀刻到基板中形成的低压室或凹坑能够在低流速下实现体积流量比引起的聚焦。单层设计简化了表面微加工，并将器件良率比之前的工作提高了 1.56 倍。聚焦设计与光波导集成，用于分析流体流动中珠子的荧光信号。研究发现，聚焦方案的实施缩小了珠子速度和荧光信号的分布，使信号的一致性提高了 33%。在低操作真空压力下观察到储层效应，并实现了光流控信号方差和强度之间的平衡。在光流控传感器中实施该设计将实现更高的检测灵敏度和样品特异性。